Abstract The goal of this proposal is to evaluate the feasibility of measuring click-evoked auditory brainstem responses (ABRs) among infants who vary in heritable risk for autism spectrum disorder (ASD) and to calculate preliminary estimates of effect size. Click-evoked ABRs are event-related potentials that reflect the electrophysiological processing of broadband acoustic stimuli (i.e., clicks) from the cochlea through the rostral brainstem. ABRs consist of 5 distinct waves (I-V) from which latencies and amplitudes can be derived, values thought to reflect the degree of dendritic branching, myelination, and synchrony of neuronal firing between nuclei in the central auditory pathway. Studies suggest that click-evoked ABR parameters and ASD are associated and that these associations are medium to large in size, particularly in children. However, it is unclear whether ABR alterations precede ASD diagnosis. To address this conceptual and empirical gap in the literature, we will compare ABR parameters between two groups of infants who vary in heritable risk for ASD: 1) babies who have an older sibling diagnosed with ASD (higher risk; n=18), and 2) gestational age- and sex- matched babies who do not have any siblings diagnosed with ASD (lower risk; n=18). Participants will be recruited at Sparrow Hospital (Lansing, MI) and invited to participate in a lab visit at one month of age (+ 1 week). At this lab visit, a licensed audiologist will perform a comprehensive middle ear examination, an ABR threshold screen, and a diagnostic-level ABR. If the etiologic and/or predictive value of ABRs is supported in subsequent investigations, the research initiated with this project has the potential to transform ASD risk surveillance and access to early interventions.